For as long as pickup trucks have existed, there has been a need for a ramp to load/unload them. In the past, such ramps were attached to truck tailgates. Alternately, the tailgate itself was removed; and the ramp, when not in use, was folded upwardly in place of the tailgate. But matching a ramp with the body of a particular vehicle is difficult, and truck owners are generally reluctant to permanently alter their vehicles.
An approach which requires substantially less alteration entails the use of heavy steel bumpers. Once commonplace, such bumpers can serve as a convenient structure on which to attach a ramp. Dudley, in U.S. Pat. No. 4,795,304, for example, uses the rear bumper for this purpose. But with the advent of plastic bumpers, his type of ramp support lost favor. Indeed, without a heavy steel structure, bumpers no longer can be used to mount a ramp or even a conventional towing ball.
In response to unmet towing needs, a combination trailer hitch receiver/hitch arm, in which the hitch receiver is fastened to the undercarriage of a vehicle, was subsequently developed. Such a hitch receiver is now available at relatively low cost for nearly all truck models. Two versions currently dominate the market. Classes II and III hitch receivers present a 1-1/4 inch by 2 inch rectangular opening and a 2 inch square opening, respectively, into which one end of an appropriately sized hitch arm can be slip-fitted. Once the hitch arm has been so slip-fitted, two sets of openings, located in the hitch receiver and arm, respectively, can be brought into alignment, so that a locking pin can be inserted therethrough and employed to hold the hitch receiver and arm in assembled relation. In a popular version of the hitch arm, a towing ball is mounted on the end thereof distal from the hitch receiver.
But none of the prior art hitch arm/hitch receiver combinations provides for a ramp which can be used to load and unload a pickup truck.